EuF₃/Ga₂O₃ Dual-Phase Nanostructural Glass Ceramics with Eu²⁺/Cr³⁺ Dual-Activator Luminescence for Self-Calibrated Optical Thermometry

To circumvent the requirement of small energy gap between thermally coupled levels of lanthanide probes in optical thermometry, a strategy using dual-activator fluorescence intensity ratio as temperature signal in dual-phase nanostructural glass ceramics was reported. Specifically, oxyfluoride glass with specially designed composition of SiO 2 –Al 2 O 3 –LiF–EuF 3 –Ga 2 O 3 –Cr 2 O 3 was fabricated, and subsequently glass crystallization was used to induce homogeneous precipitation of hexagonal EuF 3 and cubic Ga 2 O 3 nanocrystals among the glass matrix. Impressively, Eu 2+ activators were produced after glass crystallization in an air atmosphere, and the Cr 3+ emitting center was evidenced to incorporate into Ga 2 O 3 crystalline lattice. As a result, temperature determination with high sensitivity of 0.8% K –1, large energy gap of 8500 cm –1, and superior thermal stability were realized by taking advantage of the fluorescence intensity ratio between Eu 2+ and Cr 3+ as detecting parameter, which exhibited a linear dependence on temperature. We believe that this preliminary investigation will provide a practical approach for developing a high-performance self-calibrated optical thermometer.